Results to date from studies supported by Grant HD-06429-01 have shown that infants 21-25 weeks are capable of recognizing previously exposed visual targets after periods of hours, days, and weeks. Instances of failure of delayed recognition, also found, appear to be due to particular combinations of certain perceptual and temporal factors. Forgetting occurs when the infant is exposed to stimuli which bear some degree of similarity to previously acquired information. Not all similar stimuli lead to forgetting and even those that do must be presented to the infant soon after he has acquired the original information. In the proposed studies three aims will be pursued. The first is to investigate visual recognition memory for abstract targets and for targets representative of social stimuli (faces) over periods of hours, days, and weeks. The second is to explore forgetting by exposing the infant to targets perceptually related to those to be retained in the interval between immediate and delayed recognition testing. The third is to chart the temporal effects of interfering material on delayed recognition in terms of how soon interfering material must be presented following immediate recognition to disrupt delayed recognition and how long the deliterious effects of such intervention last. These aims will be pursued at two age levels, 16-18 weeks and 22-24 weeks, to make developmental comparisons with regard to the circumstances affecting infant memory and forgetting.